Strengthened with development of the electronic technology, various types of electronic products are developed and supplied, and head mounted display (HMD) devices are used, providing virtual reality services.
In general, the virtual reality technology collectively refers to those technologies that essentially aim to recreate three-dimensional virtual space for the participants so that they can be immersed in the virtually-created world by means of an interaction through all human senses (vision, hearing, smell, taste, touch) in a three-dimensional virtual environment which is created through the computer graphics (CG) technology similarly to a real environment, and also to allow the human user to be immersed in this virtual space and maximize utilization of information.
Meanwhile, in a related art, a user may have difficulty of managing emergent situation when the user is immersed in the virtual space and not able to recognize situation occurring outside. Further, the user may have difficulty of understanding an external environment or using external interface (e.g., keyboard, mouse, or the like) without taking off the HMD device when such is required.
Although some HMD devices recognize an external object and express this in augmented reality, there are inconveniences in that only registered external objects are expressed, or expression is not satisfactory, or delay time occurs.
Accordingly, a technology for the user to recognize an exterior of the HMD device with more convenient method is demanded.